Flexible solid strip type zipper made from plastic



5,19 H. ALBERTS ETAL 3,072,991

FLEXIBLE SOLID STRIP TYPE ZIPPER MADE FROM PLASTIC Filed 001',- 17, 1960 AE/PBE/Pf #4357872:

574 57 wan-22474 INVENTORS' firms of Mount Nylon, Canada;

United States atent 3,072,991 Patented Jan. 15, 1963 "ice Plastic zippers of the solid strip type, i.e., zippers comprising links joined to each other in successive order and forming one integral part with their connecting means, are well-known in the art. A disadvantage of these plastic zippers is that they have, with the exception of the so-called spiral-type zippers, unsatisfactory flexibility.

The solid strip zippers at present manufactured by the Dickermann, Germany, and Rurmann, Germany, must be embedded into the supporting tape or holder. Thus two flaps of tape partly cover the links or teeth. These flaps of tape are firmly connected with each other by means of a sewing thread passed through the intervals or gaps existing between the links of the zipper. It is the purpose of these flaps of tape to support the entire structure because otherwise a serviceable zip fastener of this type could not be obtained.

If a zipper manufactured in the manner as described above is folded crosswise, it can be seen that the tightly sewn-on tape flaps prevent the radius formed when folding from becoming too small, because the consequence of too small a radius would be that the teeth are disengaged from each other so that the zipper would spring open and thus become useless. As a matter of fact, the more the zipper can be folded in crosswise direction the greater will be the spreading of the gaps of engagement at the point of fold.

If these well-known solid strip type zippers were deprived of the tape flaps providing the coherence of their elements, these zippers would become unserviceable because their structure depends on the said tape flaps.

About 20 years ago, a zipper was developed which was covered by a supporting tape. The object of this design was to cover the elements or links of this zipper. However, it has been found in practice that zippers of this type are subjected to considerable wear so that their service life is rather limited. This is due to the fact that the locking slide performing the opening and closing movements during such movements slides over the tape and thereby causes the wear on the tape because the latter is exposed to the continual friction of the locking slide moving under tension.

It will thus be readily understood that a solid strip type zipper covered by means of a tape will never be so durable as a zipper with uncovered links which guide the locking slide directly; this is the case, for instance, with the wellknown metal zippers or with zippers having injection molded nylon or Samak links.

'It is therefore the object of the present invention to achieve the advantages of the metal zippers with a plastic zipper which is relatively cheap in manufacture.

As is well known, the metal zipper or, in other words, the zipper consisting of separate links attached to the rim of the supporting tape, therefore offers greater safety against breaking open, because cushions are formed upon crosswise folding by the uncompressed rim of the supporting tape and fill the gaps between the links so that the radius produced is limited or in other words, the formation of a minimum radius is prevented. It will be readily understood from this that the said cushions formed by the rim of the supporting tape enlarge the radius of the closed zipper. v

' These rimcushions have an extraordinarily favorable effect, because they partly fill the volume -of the gaps between the links thereby giving support and yet offer flexibility since their texture consists of fibres the elasticity of which can never be obtained at the same volume when compact plastic is used. It is also possible to arrange the fibre rim near the embossed portion of the links without thereby inhibiting the engaging movement of the links. This is due to the fact the supporting element, i.e., tape and its rim, is flexible and still gives sufficient support to the links by its volume and the arrangement of the whole system.

Various plastic zippers have already been developed on a purely theoretical basis (see U.S.A. patents of W. M. Camp, R. C. Legat, and Wolfram Ditmeier; French patent of M. M. Longhi and Sainson; German patent of T eher and Loschitz, etc.) which, however, are of hardly any importance in practice, because the so-called strips or bands have not suificient flexibility or the guide angle of the locking slide must be too great in view of the cam contour of the links provided, since the degree of safe locking of the zipper is determined by a given length of the links and height of the cams if a suitable opening and closing angle is to be maintained for the locking slide.

Experience gained over many years past in the field of zipper design has shown that the guide angle of the locking slide performing the opening and closing movements must not surpass a certain value if the zipper should 4 actually be of practical use. Actually, too great a guide angle would lead to the result that the zipper never can be closed over its entire length if it has already been connected with the object to be locked.

With well-known designs of plastic zippers, the strong intermediate connections provided between the plastic links were intended to replace the rim cushions present in zippers consisting of separate links attached to the tape which has actually been accomplished, i.e., that these intermediate connections could be so designed that they perform the function of the rim cushions during crosswise folding of the zipper. However, with these wellknown designs there is the disadvantage that the opening and the closing movements of the zipper has proven to be extremely difficult because the hinge-like movement of the links mounted on a rigid support gives rise to a considerable resistance.

Zippers of this well-known type are relatively stitr', they move heavily and practically find no application, thus they are not marketable.

From that which has been explained above, it is evident that it is possible with solid strip type zippers made from plastic and covered by means of tape flaps to provide a flexible or relatively thin plastic connection between the individual elements. But it also becomes apparent that the locking slide is directly in contact with the tape and during its closing movement must necessarily cause considerable wear to the tape, and which is dueto the frictional and tensional contact between the slide and the tape This invention has therefore for its object the provision of a favorably priced plastic zipper of the solid strip type which offers the advantages of zippers comprising separate links attached to a supporting tape with rim, and with which the locking slide is guided directly by the links without the use of further auxiliaries, such as tape flaps or guide strings. The invention also contemplates not to deviate essentially from the shape of the head portion of the links of conventional metal zippers, which has long given satisfactory results, in order to ensure a favorable ratio of the length of the link to the height of the cam, i.e., a satisfactory engagement of the links with one another and to obtain a guide angle of the locking slide which permits a smooth movement.

The advantages such as strength in every respect,

smooth sliding movement and reduced manufacturing costs are the characterizing features of the zipper conceived and manufactured in accordance with the invention.

In the drawings:

FIG. 1 shows a continuous shaped piece in side elevation;

FIG. 2 is a sectional view of the shaped piece shown in FIG. 1;

FIG. 3 is the side elevation of the sequence of elements or solid strip obtained by milling the shaped piece, FIGS. 1 and 2;

FIG..4 is a top view of the milled solid strip of FIG. 3;

FIG. 5 is a sectional view taken in a plane identified by line 5-5, FIG. 3;

FIG. 6 is the top shaping;

.FIG. 7 shows theshaped solid strip in side elevation;

'FIG. 8 is a sequence of elements provided with double projections in side elevation, and FIG. 9 is the side elevation of a species wherein projections are provided on the side of the elements opposite to the projecting engagement teeth.

The hooks of the one piece stringer are formed by milling out a shaped piece of plastic (FIG. 1) which has a continuous hollow space 2 and which may alternately be omitted. Each hook has two facial projections one of which, 3, lying opposite the cord section 6', forms a head or tooth of contact 1'. The second projection or base 2' between which cord sections 6' extend, surpasses in length the first mentioned projection forming the tooth of contact 1'. The projection or base 2' serves as a support for the elements, so that the formation of too small a radius during crosswise folding of the closed zipper, which would cause breaking of the zipper, is prevented. It is also possible, for instance, to provide each of the elements with two projections 2', as shown in FIG. 8, or, alternatively, the elements or links of the zipper according to the invention may be provided with one projection 7 as shown in FIG. 9. When milling out the transverse gaps asclescribed above, a relatively thin bridge or cord section 6 is left between the remaining portions of the shaped piece. See FIG. 5.

Cord section 6 is so arranged (FIGS. 3, 4, 5, 6 and 7) that, it has an almost central position, i.e. that it is adjacent to the periphery of the necessary space of movement of the intermeshing elements. FIG. '3 showsa cord 6" which is relatively thin and flat because it extends only from the vertex of the inwardly extending recess or channel 5' of the shaped piece. It is thereby achieved that connecting cord 6 is located relatively close to. the center of the link whereby the necessary flexibility is maintained in view of the relatively small cross-section of, the cord. The shaped elements so obtained is, after completion of shapi 2, woven onto an appropriate tape of fabric by means of warp thread.

The recess 5' (FIGS. 2 and 5) favors the application of the tape or the proper positioning of the link strip, respectively.

The projections 'or bases 2' constitute one of the principal features of this invention inasmuch as they reduce the gaps between the links arranged in a successive row at the level of their bases or. support. Owing to this structural feature -it is possible to make said gaps 3' smaller than the opposite gaps 4 provided between the teeth of contact. See FIGS. 6 and 7.

It will therefore be understood that said projections, bases or supports 2' prevent with their edges any lifting out of engagement of the hook-shaped links by lever action, because, as a matter of fact, the gaps 3' are already closed and the radius of fold is limited with any crosswise foldingof the closed zipper before a lever action can be exerted onthe intermeshing elements. Any dis engagement of the locked teeth or hook-shaped links is view of the milled solid strip after sequence of hookof the locking slide, flexibility 4 thus prevented and a zipper which cannot break open is obtained without further auxiliary means such as tape flaps or guide strings attached by sewing.

Since the locking slideof the zipper according to the invention is directly guided by the plastic parts, it will be readily understood that, apart from the saving ofmanufacturing costs, a considerably greater durability and improved resistance to stress is obtained when compared with well-known plastic zippers of the solid-strip type.

In the claims, the expression median plane of the stringer means a plane which is normal to theplanes of FIGURES 4 and 6, and mid-way between the upper and lower lines defining cord sections or interconnections 6. The bottom surface of each base is the surface, for example, normal to the plane of FIG. 3 and defined by the lower lines of these bases in said figure. The longitudinal dimension or direction of the stringer is the direction in which the slide travels along the fastener in opening and closing the same. An element of cord sections 6' is any 2 line in the surface thereof parallel with the aforesaid longitudinal dimension.

We claim:

l. A slide fastener stringer comprising a one-piece, continuous flexible strip including hooks interconnected in uniformly-spaced relation by cord sections, each said hook comprising a tooth having a projection extending in the direction longitudinally of said stringer, a base, and an intermediate portion interconnecting said tooth and base in transversely-shaped relation and of lesser dimension in said longitudinal direction, than said tooth and base, each said cord section lying in the median plane of the stringer between the bases only of said hooks and offset inwardly from the bottom surfaces thereof, each said cord section having a length less than the dimensions of the tooth and base in said direction and a transverse cross section less than that of said base.

2. A slide fastener stringer as in claim 1, the bottom surface of each said hook having a channel, along and symmetrical with respect to, said median plane, the line intersected by said median plane, in the surface of said channel being essentially coincident with the element of said cord section nearest the bottom surface of said bases.

3. A slide fastener stringer as in claim 1, said intermediate portion having a passageway therethrough in said direction, there being a longitudinally-extending channel in the, bottom surface of said base, said passageway and channel being symmetrical with respect to said plane, diametrically-opposite elements of said cord sections being substantially tangent to said passageway and channel, respectively. 4. A one-piece slide fastener stringer comprising, a plurality of uniformly-spaced hooks, each said hook comprising a tooth projecting in the longitudinal direction of the stringer, a base, and an intermediate portion of lesser dimension in said direction than said toothvand base and interconnecting the same in spaced'relation transversely of said direction, and cord sections sequentially interconnecting said bases only in longitudinally-spaced relation, each said cord section having a cross-sectional area in planes normal to said direction, greatly reduced over the corresponding cross sectional area of said base, and extending in and along the median plane of the stringer, intransversely inwardly oifset relation with the bottom surfaces thereof.

5. A slide fastener as in claim 4, each said cord section having a length less than the dimensions of said base and tooth in said direction.

6. A slide fastener as in claim 4, said tooth and intermediate portion each having one surface only thereof in a common first plane normal to said direction, and said base having an end surface in a second plane normal to said direction and spaced outwardly of said first plane.

7. A slide fastener stringer as in claim 4, said tooth, base, and intermediate portion each having one end surface only in a common plane normal to. said direction.

8. A slide fastener stringer comprising an integral onepiece'continuous strip of plastic and including enlarged, uniformly-spaced hooks, each said hook comprising a tooth having a first projection extending longitudinally of said stringer, a base having a longitudinal dirnension not less than the corresponding maximum over-all dimension of said tooth, and an intermediate portion of lesser longitudinal dimension than said tooth and base and interconnecting the same in transversely-separated relation, and flexible cord sections interconnecting said hooks in longitudinally-spaced relation, said cord sections lying in and along the median plane of said stringer and extending between and interconnecting said bases only, adjacent said intermediate portions, each said cord section having transverse dimensions less than the corresponding dimensions of said base, each said cord section being otiset 6 transversely inwardly from the bottom surfaces of the bases interconnected thereby, and a fabric strip secured to and along said bases, in edge contact with the bottom surfaces thereof, by warp threads in the selvage edge thereof looped over and about each said cord section.

References Cited in the file of this patent UNITED STATES PATENTS 2,226,095 Garrison Dec. 24, 1940 2,397,331 Winterhalter Mar. 26, 1946 2,525,284 Camp Oct. 10, 1950 FOREIGN PATENTS 408,797 Italy Ian. 10, 1945 746,546 Great Britain Mar. 14, 1956 762,226 Great Britain Nov. 28, 1956 

1. A SLIDE FASTENER STRINGER COMPRISING A ONE-PIECE, CONTINUOUS FLEXIBLE STRIP INCLUDING HOOKS INTERCONNECTED IN UNIFORMLY-SPACED RELATION BY CORD SECTIONS, EACH SAID HOOKS COMPRISING A TOOTH HAVING A PROJECTION EXTENDING IN THE DIRECTION LONGITUDINALLY OF SAID STRINGER, A BASE, AND AN INTERMEDIATE PORTION INTERCONNECTING SAID TOOTH AND BASE IN TRANVERSELY-SHAPED RELATION AND OF LESSER DIMENSION IN SAID LONGITUDINAL DIRECTION, THAN SAID TOOTH AND BASE, EACH SAID CORD SECTION LYING IN THE MEDIAN PLANE OF THE STRINGER BETWEEN THE BASES ONLY OF SAID HOOKS AND OFFSET INWARDLY FROM THE BOTTOM SURFACES THEREOF, EACH SAID CORD SECTION HAVING A LENGTH LESS THAN THE DIMENSIONS OF THE TOOTH AND BASE IN SAID DIRECTION AND A TRANSVERSE CROSS SECTION LESS THAN THAT OF SAID BASE. 